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Finding the Fourth Proportional to 72.42, 108.45 and 45.31

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Solution

The fourth proportional to 72.42, 108.45 and 45.31 is: 67.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.42 : 108.45 = 45.31 : x
  2. Step 2: Convert to fraction form
    72.42/108.45 = 45.31/x
  3. Step 3: Cross multiply
    72.42x = 108.45 × 45.31
  4. Step 4: Simplify right side
    72.42x = 4,913.87
  5. Step 5: Solve for x
    x = 4,913.87/72.42
  6. Step 6: Final answer
    x = 67.85

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.